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/*! \file
    \brief Template wraps the vector access iterator concept to load whole
   vector from tensors in memory. This is typically used for per-channel scale
   and bias in convolution kernels.
*/

#pragma once

#include "cutlass/transform/threadblock/predicated_vector_access_iterator.h"

/////////////////////////////////////////////////////////////////////////////////////////////////

namespace cutlass {
namespace transform {
namespace threadblock {

/////////////////////////////////////////////////////////////////////////////////////////////////

template <typename VectorAccessIterator_>
class VectorIterator {
public:
    using VectorAccessIterator = VectorAccessIterator_;

    using Shape = typename VectorAccessIterator::Shape;
    using Element = typename VectorAccessIterator::Element;
    using Layout = typename VectorAccessIterator::Layout;
    using TensorCoord = typename Layout::TensorCoord;
    using AccessType = typename VectorAccessIterator::AccessType;
    using TensorRef = typename VectorAccessIterator::TensorRef;
    using Index = typename VectorAccessIterator::Index;
    using LongIndex = typename VectorAccessIterator::LongIndex;

    static int const kElementsPerAccess =
            VectorAccessIterator::kElementsPerAccess;
    static int const kRowsPerIteration =
            VectorAccessIterator::kRowsPerIteration;
    static int const kThreads = VectorAccessIterator::kThreads;
    static int const kIterations = VectorAccessIterator::kIterations;

    /// Fragment object to be loaded or stored
    using Fragment = cutlass::Array<Element, kElementsPerAccess * kIterations>;

private:
    /// Internal state
    VectorAccessIterator vector_access_iterator_;

public:
    /// Constructor
    CUTLASS_HOST_DEVICE
    VectorIterator(Element const* ptr, TensorCoord extent, int thread_idx,
                   int warp_idx,
                   MatrixCoord const& threadblock_offset = MatrixCoord())
            : vector_access_iterator_(ptr, extent, thread_idx, warp_idx,
                                      threadblock_offset) {}

    /// Advances to the next tile in memory.
    CUTLASS_HOST_DEVICE
    VectorIterator& operator++() {
        vector_access_iterator_.advance();
        return *this;
    }

    /// Advances to the next tile in memory.
    CUTLASS_HOST_DEVICE
    VectorIterator operator++(int) {
        VectorIterator self(*this);
        operator++();
        return self;
    }

    /// Loads a fragment from memory
    CUTLASS_DEVICE
    void load_with_pointer_offset(Fragment& frag, Index pointer_offset) {
        frag.clear();
        AccessType* frag_ptr = reinterpret_cast<AccessType*>(&frag);

        CUTLASS_PRAGMA_UNROLL
        for (int c = 0; c < kIterations; ++c) {
            cutlass::arch::global_load<AccessType, sizeof(AccessType)>(
                    frag_ptr[c], vector_access_iterator_.get() + pointer_offset,
                    vector_access_iterator_.valid());

            ++vector_access_iterator_;
        }
        //    }
    }

    /// Loads a fragment from memory
    CUTLASS_DEVICE
    void load(Fragment& frag) {
        vector_access_iterator_.set_iteration_index(0);
        load_with_pointer_offset(frag, 0);
    }

    CUTLASS_DEVICE
    void advance() { vector_access_iterator_.advance(); }
};

/////////////////////////////////////////////////////////////////////////////////////////////////

}  // namespace threadblock
}  // namespace transform
}  // namespace cutlass

/////////////////////////////////////////////////////////////////////////////////////////////////
